One method of repairing a muscle wall defect or hernia of a patient's abdominal wall muscle is to insert a prosthetic material or mesh through the defect and so as to be inside the patient's muscle wall. The prosthesis, which is generally larger than the defect, is then positioned in a planar orientation relative to the muscle wall, covering the defect in its entirety. The prosthesis is then typically fixed to the underside of the muscle wall or tissue surrounding the defect, with the use of fixation tools such as sutures and/or tackers.
A second method of repairing a hernia is to place the prosthetic material or mesh through the muscle wall defect, and position it in a planar orientation between the muscle wall and the posterior sheath.
Prosthetic devices have recently been developed that aid in the orientation, positioning and fixation of the prosthesis to the underside of the muscle wall defect. These devices generally consist of (a) a prosthesis or base that may be folded and placed through the defect; (b) a support member or washer that is combined with the prosthesis and that urges the prostheses into a planar orientation after it has been placed through the defect; and (c) a handle or positioning straps that can extend through the defect and can be used to hold the prostheses close to or against the muscle wall while the prosthesis is sutured or tacked to the abdominal wall. At least a portion of positioning straps are subsequently cut off once the prosthesis is fixed in place, allowing tissue anterior to prosthesis and muscle wall to be sutured closed.
U.S. Pat. No. 7,101,381 describes a prosthesis comprising a resilient support member disposed on a patch, the resilient support member being constructed and arranged to urge the patch into a planar configuration. This additional support member, attached to the layers of the prosthesis, however, is permanently implanted in the patient and introduces additional stiffness or rigidity, which may interfere with the prosthetic's ability to conform to the contours of the patient's abdominal wall. This arrangement makes it more difficult to ensure that the patch remains flat against patients' moving and contoured abdominal wall. The flat and tight junction between the patch and the patients' abdominal wall is necessary for ensuring that intra-abdominal tissue or bowels cannot become wedged between the prosthetic and the abdominal wall, causing a hernia recurrence (particularly for the first method of repairing a hernia described above).
US patent US2011/0144667 attempts to resolve the high degree of stiffness that results from this support member by describing a support washer that is not attached or sutured to the base of the prosthetic, but is instead free-floating. This washer of this device is still, however, contained within the enclosed layers of the prosthesis, and permanently implanted with the prosthesis. While this prosthesis may reduce some of the stiffness when compared to the support member described in U.S. Pat. No. 7,101,381, the reduced stiffness also compromises the ability of the support washer to urge the prosthesis into a planar configuration. Because surgeons must ensure that this prosthesis is in a planar configuration and the prosthesis completely covers the muscle wall defect, many find this device difficult to use.
Both the additional support member described in U.S. Pat. No. 7,101,381, and the free-floating support washer described in US2011/0144667 introduce additional foreign body material that is implanted into the patient. This additional foreign body material not only itself adds rigidity to the abdominal wall, it further compromises the flexibility and physiological function of the abdominal wall by eliciting a foreign body response that results in a stiffer and weaker muscle repair around the prosthetic.
One familiar with the art will recognize the importance of fixing the patch, particularly the peripheral edge of the patch, to the abdominal wall. This facilitates a tight junction between the patch and the muscle wall, and facilitates integration of the patch to the abdominal wall over time. Underlying tissue or organs cannot then become wedged between the patch and the abdominal wall, which could otherwise lead to an incomplete repair, a hernia recurrence, or other post-operative complications.
U.S. Pat. No. 7,101,381 goes on to describe a patch that has an access opening that is adapted to provide entry into the inferior of the pocket (between the layers) to facilitate the positioning of the patch over the tissue or muscle wall defect. This pocket may also be accessed by sutures or a tacker in order to fix the patch to the abdominal wall. However, once the patch has been positioned relatively deeply within the abdominal wall, it is difficult or even impossible for a surgeon to see the access opening of the patch during fixation. It is thus very challenging for the surgeon to place instrumentation through the muscle wall defect (which is typically smaller than the patch), into the access opening of the patch, and fix the peripheral edge of the patch to the underside of the abdominal wall, without unintentionally perforating the patient's organs, tissue or other critical structures.
The resilient support member that U.S. Pat. No. 7,101,381 describes and that urges the patch in the planar configuration is disposed on the patch. This support member, and the stitching that disposes the resilient member onto the patch, become the perimeter of the access opening, and a barrier that prevents access through the access opening or pocket, to the peripheral portion or edge of the patch. It is therefore not possible to suture or tack the peripheral portion of the patch to the abdominal wall from within the access opening of the patch. This can prevent complete integration of the patch to the abdominal wall, and can allow patient tissue or organs to be wedged between the patch and the abdominal wall.
In application published as 2014/117270, to Stephen Pankratz, the contents of which are incorporated herein, there is described a prosthesis and placement device which is configured to facilitate insertion, positioning and removal of the support. The placement device includes a support that is insertable in to the prosthesis and has a handle attached to the support. The handle is provided with sufficient stiffness to impart a bending moment to the support. The support has a generally planar surface with a zone of weakness that facilitates movement of the support between a deployed position, in which the prosthesis is supported and a collapsed position for insertion in to and removal from the prosthesis. Proper support for the prosthesis enables the surgeon to insert sutures or staples to secure the prosthesis and mitigates the risk of the suture being misdirected. The zone of weakness in combination with the stiffness of the handle enables the support to be collapsed once the prosthesis is properly secured.
The forces required to collapse and extract the support should be minimized to avoid damage to the tissue surrounding the incision in the abdominal wall as the support is removed. The device shown in US patent publication 2014/117270 maintains the forces required for removal at acceptable levels but in certain circumstances a further reduction is desirable.
It is an object of the present invention to provide a support device for a prosthesis which seeks to attain a further reduction in such forces.